evolution exam 2

pratical species concept

"in determining whether a form should be ranked as a species or a variety the opinion of naturalists have sound judgement and wide experience seems the only guide to follow"

Ecographic Isolation

-given sufficient time and divergence 2 species may become so different they cant return to sympatric -geographically isolated product of reinforcement for 2 incompatible habitats

Macroevolution

-produces irreversible changes -takes alot of time

selection for a multi-niche polymorphism

specialization can lead to a sympatric divergence by distributive selection

index of species concept (part 2)

-" the importance of data is that they give us something to think about" - "the inability to distinguish may be a deficiency of our methodology rather then a failing of our conept"

seasonal isolation

-2 incipient species that are sympatric but breed assortively at different times (isolation in reproductive time)

behavioral isolation

-2 incipient species thats based on behavior of species based on the concepts of mating signals and rituals -auditory, visual and chemical

habitat isolation

-2 populations occupy different habitats in a sympatric zone -preference for habitat leads to assortive mating and is reinforced by habitat

typological species concept

-Defining species as distinctively different groups based on physical similarities -species are unique types formed by special creation -species are fixed, well-defined, distinct, non-dimensional, and unchangeable -the type is chosen to reflect the species -variation is allowed but only to the extent that it doesn't fall outside the type limits -variation doesn't change the overall complexion of species -"individuals are imperfect casts from the perfect mold of the type" -works well with bigger collections -largely displaced by Darwinian thought

peripheral isolate

-a small, isolated population on the periphery of the range -the land moves around the species

evolutionary species concept

-a species is a single lineage of ancestral descendent populations of organisms which maintains its identity from other such lineages and which has its own evolutionary tendency and historical fate -a species is a single lineage evolving together -it doesnt apply actual or potential sharing of a common gene pool -implies that gene flow can occur but it doesnt have to -implies BSC is valid but doesnt consider everything it needs to -recognizes that species can diverge even if gene flow is high if you have strict differential microevolutionary pressures -species dont seize to exist when they lose there evolutionary tendency thru divergence we recognize there generalized features which give meaning of higher level of taxonomic groups -"evolutionary species make history, higher level taxonomic groups are history" -not worried about gene pool but with tendency and historical fate

Haldanes rule

-among hybrids offspring if 1 sex is absent, rare, or sterile its heterozygous sex -heterogametic hybrids have decreased fitness and that is the basis for reproductive isolation

morphological species concept

-characterizes a species by body shape and other structural features -species that share a common structure -different from typological because it recognizes variation -recognizes evolutionary concept -still the best way to recognize a species based on structure -doesnt reject: heritability or a shared gene pool -it doesnt use these features to define species

parapatric speciation

-core concept is the cline -a cline must exist at species distributional interference -cline=spatial gradient of genotypes and phenotypes that exist because of adjacent incipient species observe different pressures -requires a hybrid zone at the species interference

Biological Species Concept (BSC)

-current concept used -a species is a array of populations, members which interbreed when in contact in nature (or connected by interbreeding populations) or are capable of doing so. If not prevented by geological or time variants (is sympatric with synchronous breeding cycles). if hybridization occurs it does so in such a matter that the complexion of populations is unchangeable -affects populations not individuals -recognized gene flow thru interconnected populations -recognizes unused potential across space and time

allopatric speciation

-depends on physical genetic isolation -genetic isolation is the easiest way to allow other microevolutionary mechanisms to produce divergence -depends on physical or geographic barriers to hault gene flow -Mayr 1942- "if geographic isolation prevents gene flow incipient species can diverge by differential mutation, selection, and drift alone"

Dobzhansky-Muller incompatibility

-depends on the notion of incipient species -strains that "self isolates" but are incompatible on future contact -depends on the rise mutually exclusive mutations in the 2 incipient species

Reinforcement

-divergent species are adaptive to there own habitats but hybrid species are at a disadvantage to both habitats -strong selective pressure against hybrids -depends on selection for species isolating mechanisms

adaption

-ecological phenomena -variation in phenotype over a cline but within a single genotype

adaptation

-evolutionary phenomena -depends on genotype and variation on phenotype

parapatric speciation

speciation occurring when two populations have continuous distributions and some phenotypes in that distribution are more favorable than others

what is a species?

-species are groups of organisms that we name with a set of biological characteristics -characteristics for species are discontinuous -species are based on discontinuities that make them unique -larger taxonomic units are different based on similarities of their consistent taxa

6 processes of macroevolution

1. adaptation 2.convergence 3.divergence 4.stasis 5.speciation 6.extinction

why you might not be able to group them

1. convergence -2 groups that don't show but have common ancestry 2. parallelism -2 taxa that share a recent evolutionary response and derived the same character independently

4 major contributions of the BSC

1. deals with the historical aspect of speciation 2. incorporates multiple criteria but it limits there individual force and weight 3. based on populations not individuals 4. based on potential to share a common gene pool

isolating mechanisms

1. ecogeographic 2. habitat 3. seasonal 4. behavioral 5. mechanical 6. gametic 7. developmental 8. hybrid inviability 9. hybrid sterility 10. selective hybrid elimination

populations exist in 3 dimensions

1. geographical 2. geological time 3.gene flow

dichopatric model predictions

1. if vicariance led to speciation sibling species should occur at either side of the isthmus 2. sibling species should be less tolerant, more aggressive and less reproductively compatible the longer they've been isolated 3. deep water shrimp should of been isolated first thus they should have more divergence and more genetic distance than shallow water species

criticisms of evolutionary species concept

1. leads to the profilation of names -if there's actually species they need a name 2. is it operable? can we actually use it or is it just a good theory? -every new idea becomes operational when people learn how to use it -just because you don't know how to use it doesn't mean it's useless

3 models of parapatric speciation

1. reinforcement (ecological neutral equilibrium model) 2. ecologically bounded hybrid superiority 3. ring speciation

3 models of sympatric speciation

1. selection for a multi-niche polymorphism 2. Debzhansky-Muller incompatibility 3. Hadans rule

limitations of macroevolution

1. tends to model it that isolation and divergence occur separately but they can occur at the same time and place 2. in many species secondary contact doesn't happen 3. sometimes secondary contact provides the mechanism to drive speciation instead of just testing it

3 historical substantial failures to BSC

1. the rule of gene flow as a cohesive force in holding species together -2 non-diverging populations that dont have gene flow even tho its possible and thus this implies theres something more then gene flow holding the species together -it doesnt take very much gene flow and it doesnt have to be constant to hold them together -it cant work cuz 2 species that dont have gene flow cant diverge -mutation rate might make them diverge but not always depending on mutation rate 2. why place so much weight on interbreeding and gene flow when theyre so many other discontinuities availabe? -not ignoring discontinuities but using them as evidence for interbreeding and gene flow 3. how does the BSC apply to asexual species? -worried about gene pool of population not the genome of an individual -only the species itself possesses all the possible features in evolutionary arena -gene flow has to exist on the population level but no requirement for gene flow for an individual

3 historical substantial failures to BSC

1. the rule of gene flow as a cohesive force in holding species together -2 non-diverging populations that don't have gene flow even tho it's possible and thus this implies there's something more then gene flow holding he species together -it doesn't take very much gene flow and it doesn't have to be constant to hold them together -it can't work cuz 2 species that don't have gene flow can't diverge -mutation rate might make them diverge but not always depending on mutation rate 2. why place so much weight on interbreeding and gene flow when they're so many other discontinuities available? -not ignoring discontinuities but using them as evidence for interbreeding and gene flow 3. how does the BSC apply to asexual species? - worried about gene pool of populations not the genome of an individual - only the species itself possesses all the possible features in evolutionary arena -gene flow has to exist on the population level but no requirement for gene flow for an individual

index of species concept

1. typological, still in use, not viable 2. practicle, not still in use, not viable 3. morphological, still in use, is viable -physiology -behavioral -serological -genetic -fertility linked 4. biological, still in use, still viable 5. evolutionary, still in use, is viable

a successful species concept must

1. universal validity 2. testable hypothesis 3. allow for special cases 4. deal with species as temporal, genetic, epigenetic, ecological, evolutionary, physiological and behavioral enitites 5. define what is and what is not possible

Which of the following is an example of a post-zygotic reproductive barrier?

A horse and a donkey breed successfully to produce a mule, which is sterile

which of the following is an example of sympatric speciation

A population of bears prefers red berries. At some point, part of the population develops a preference for blue berries. Eventually, the two groups no longer interact to the point that they no longer breed.

Which scenario is an example of allopatric speciation?

A river separates members of a squirrel population that used to occupy the same geographical area

Which of the following is true regarding speciation? A.All of these B. Allopatric and sympatric speciation are two major types of speciation C. Barriers to reproduction are critical in speciation D. It is an outcome of evolution

A. All of these

Which of the following is a NOT potential outcome from a speciation hybrid zone? A. A weakening of reproductive barriers, allowing the two species to fuse B. All of these are potential outcomes C. A strengthening of reproductive barriers, and eventual extinction of the hybrids D. The continued production of hybrid individuals

B. All of these are potential outcomes

What is required for sympatric speciation to occur?

Emergence of a reproductive barrier

Which of the following is not an example of a reproductive barrier?

For a certain species of walrus, males defend large groups of females called harems. Typically, one male's harem will consist of about 20 females, and he will mate with all of them. Some male walruses don't have harems.

A horse and a donkey can successfully mate to produce an offspring known as a mule. Mules are sterile, display a mixture of donkey and horse traits, and have a different number of chromosomes from both parent species. Would mules be classified as their own species?

No; due to their inability to reproduce successfully mules would not be classified as a new species

Which of the following reasons could explain why sympatric speciation is more common in plants than in animals?

Plants are more likely to be able to self-fertilize

Which of the following would be considered an example of conditions leading to allopatric speciation?

Separation of a population of lake fish by a drought resulting in a sand bar dividing the lake

speciation

Speciation is a process in which one species diverges into two. Two major types of speciation are allopatric and sympatric speciation, with each type featuring a unique barrier to reproduction that halts genetic exchange between populations.

Which is not an example of behavioral isolation?

Species of fish living in different areas of a pond due to differential salt concentrations

allopatric speciation

The formation of new species in populations that are geographically isolated from one another.

sympatric speciation

The formation of new species in populations that live in the same geographic area

homologue

a chromosome that is similar in appearance and genetic information to another chromosome with which it pairs during meiosis; also called homologous chromosome

A population of rabbits lives in a forest in the Southeastern United States. A large group of rabbits is cut off from the population when a six-lane highway is built through the forest. Over many generations, the large group of rabbits begins to develop darker fur in response to the dominant foliage on one side of the highway. When rabbits from the two populations are brought together, they no longer reproduce with each other. What kind of speciation does this represent?

allopatric

Peripatric speciation is a subgroup of which of the following types of speciation?

allopatric

A physical barrier separates a single species, causing two separate populations to form. Over time these two populations adapt to their environments. Eventually, these two populations are no longer able to successfully reproduce with each other. This is known as __________.

allopatric speciation

There was once a population on planet M311, called the Freg, who lived on a planet not unlike Earth. At the height of the Fregs technology and evolution, a collection of asteroids bombarded the planet and the devastation was so great that the planet was split in two, as was the Freg population. Much of the Freg population died, but many still survived on both pieces of M311. As time progressed following the catastrophe, the genetic structure of the Freg populations began to differ from each other since they were no longer reproducing with each other. What is this process called?

allopatric speciation

3 models of speciation

allopatric, parapatric, sympatric

Which of these animals would be least likely to undergo allopatric speciation?

bird

divergence

changes in 2 or more related populations that lead to increasing differences over time

convergence

changes in 2 or more unrelated species that make them more similar over time

The wing structures of bats and birds are examples of which of the following?

convergent evolution

In which of the following habitats is gametic isolation common?

coral reef

Models of Allopatric Speciation

dichopatric and peripheral isolates

Which of the following is not true regarding zygote mortality?

fertilization does not occur

Which of the following best defines sympatric speciation?

formation of two distinct species within the same geographic location

In cases of mechanical isolation, what is the barrier to reproduction between two species?

genital incompatibility

Which of the following best describes the initial speciation event in allopatric speciation?

geographic isolation

What is true regarding temporal isolation?

it is a barrier that prevents fertile individuals from meeting

Hennig's auxiliary principal

never assume convergence or parallel evolution always homology in the absence of contrary evidence

adaptation

occurs when a trait is reinforced by natural selection because it confers a specific survival or reproductive advantage

Polarized Characters

one in which the pleisoiomorphical/apomorphic direction is known

which of the following is not geographic barrier to speciation

plant polyploidy

In hybrid sterility, at what stage does reproductive isolation occur?

post-zygotic

While donkeys and horses have ignored each other historically in the wild, hybrids can be made through artificial insemination. The resulting hybrids are unusual in that they are generally viable, but always sterile. Because of their sterility, a blended lineage of the two animals cannot exist. What evolutionary force is this an example of?

post-zygotic barrier

What are the two major classifications of barriers to reproduction?

pre-zygotic and post-zygotic

which of the following is false of sympatric populations

sympatric populations diverge due to geographic isolation

One species of organisms living in the same valley begin to diverge from each other over time and eventually two distinct species emerge that no longer mate with members of the other group. What type of speciation is this?

sympatric speciation

grouping rules

synapmorphes are evidence for common ancestry relationships

A researcher has discovered two species of frogs that live in the same location. In the lab he is able to generate a viable hybrid by combining gametes from each species, however, no such hybrids exist in the wild. Which of the following methods of reproductive isolation might explain this phenomenon?

temporal isolation

Different fish living in the same pond mate at different times during the year. What type of reproductive isolation is this?

temporal isolation

dichopatric speciation

the range of a existing species is split by a vicarious event and could be slow or rapid

Which of the following describes how parapatric speciation differs from peripatric speciation?

there can be contact between the two diverging populations in parapatric speciation

Inclusion/Exclusion Rule

transformation series that aren't contradictory can be added to reconstruct evolution

Two populations of the same species over time grow distant from one another. At what point will these two populations be considered different species?

when they are no longer able to interbreed